What Are Neodymium Rare Earth Magnets?
Neodymium magnets are the strongest permanent magnets available and, even if you've never heard of them before, you probably use them every day. They're sometimes called NdFeB, or Neo magnets, and despite being so strong, they're also lightweight, which is why they're popular for a wide variety of applications. It's hard to believe, but without this type of rare earth magnet, many of the technological advances that have taken place over the past few decades would not have been possible!
How Strong Are Neodymium Magnets?
Very strong. They will amaze you! A 2-gram (0.07 ounce) neodymium magnet that measures 8 millimeters (0.315 inches) in diameter and 5 millimeters (0.197 inches) long generates a force of over 1700 grams (3.75 pounds). They re so strong that they have replaced other types of magnets in many applications. For example, they are over ten times stronger than ceramic magnets, so you might replace a ceramic magnet with a much smaller neodymium magnet and generate the same (or more!) holding force. Beware — they're also so strong that even small neodymium magnets can cause bodily harm. We've even heard of larger neos breaking bones. Handle with care!
What Are Neodymium Magnets Made Of?
Neodymium magnets are made primarily from an alloy of neodymium, iron, and boron. The exact composition can vary depending on the strength needed and what that magnet is being used for. There are two main manufacturing types for neodymium magnets: sintered and bonded.
Sintered neodymium magnets are made by heating the alloy components in a furnace, then this mixture is cast into molds and cooled to form ingots which are ground into a fine powder and pressed into molds. The molds of powder are sintered to become dense blocks. ( Sintering is the process of compacting and forming a solid mass of material by heat or pressure without melting it to the point of liquefaction.) The material is cut into its final shape, coated or plated, and then magnetized.
Bonded neodymium magnets combine neodymium alloy powder with a polymer binder. The components are pressed or extruded to make more complex shapes and magnetization powders than are typically available in sintered magnets.